A number of surfactants are known which are suitable for household cleaning products, personal care products, cosmetics, food emulsifiers and the like. However, many of the conventional surfactants are made by techniques which have intermediates that are formed in low yields making the overall process inefficient. Other preparatory methods use organo-halo intermediates which are often undesirable for potential toxicity and environmental reasons.
European Patent Application 0544478 A1 describes novel fatty acid esters of alkoxylated isethionic acid having the formula: ##STR1## where R.sub.1 is an alkyl group having 8 to 18 carbon atoms, m is an integer from 1-4, R.sub.2 and R.sub.3 are hydrogen or an alkyl group having 1-4 carbons, and M.sup.+ is a monovalent cation, and compositions comprising these compounds. These esters are made by first preparing an alkoxylated isethionate via the sulfonation of a corresponding chloroalkoxy lower alcohol (e.g. 2-(2-chloroethoxy)ethanol) and subsequently treating the sulfoalkoxy lower alcohol (e.g. 2-(2-sulfoethoxy)ethanol) so formed with an alkoyl chloride where the alkoyl group has 8 to 18 carbons (e.g. lauroyl chloride) to form the above-mentioned ester. Note the presence of two halogenated intermediates.
Carbonated isethionate surfactants and methods for obtaining them are disclosed in U.S. Pat. No. 5,232,633. The surfactants have the formula: ##STR2## where n is a number from 0 to 10; x is 1 or 2; R.sub.1 through R.sub.4 inclusive may be independently hydrogen, aryl, cycloalkyl, alkylaryl, alkylene or straight or branched C.sub.1-18 alkyl; and where M.sup.+ is alkali metal, alkaline earth metal, ammonium or alkylammonium. These surfactants are made by reacting selected alcohols and alkoxyalcohols with phosgene followed by reactions with sodium isethionate. Phosgene is, of course, a very toxic chloride-containing gas; it would be desirable if its use could be avoided.
U.S. Pat. No. 4,275,013 discusses a process for the preparation of salts of alkanesulfonic acids, which are referred to as alkanesulfonates, by the addition of alpha olefins to bisulfite in a cosolvent system consisting of water and an organic hydroxyl-containing compound in the presence of a free radical initiator.
An improved process for producing ethoxylated isethionates in an aqueous medium is provided in U.S. Pat. No. 3,823,185. In the process, the selectivity of ethylene oxide to the desired ethoxylated products is significantly increased by removal of all or a substantial part of the water present in the early stages of the reaction after a small amount of ethylene oxide has reacted. Additionally, ethoxylated isethionates having from about 2 to about 30 ethylene oxide repeating units and containing less than 25% undesirable glycol by-products are provided.
A skin cleansing composition is provided that includes a combination of C.sub.16 -C.sub.18 acyl isethionate ester salts having no more than 25% C.sub.14 or lower acyl groups with at least one co-active surfactant according to U.S. Pat. No. 4,954,282. The weight ratio of acyl isethionate to co-active surfactant ranges from about 20:1 to about 1:1.
U.S. Pat. No. 4,267,123 describes an improved method for preparing propane sulfonates by the addition of metal bisulfites to allyl ethers, amines and sulfides, where a substantial amount of the desired product is added to the reaction mixture.
Three patents are known which relate to the reaction of bisulfite with olefins. U.S. Pat. No. 3,943,174 discloses a process for producing alkyl sulfonates by the addition of bisulfite ions to olefinic double bonds. In the process, ammonium, or an alkali metal bisulfite and olefins having from about 8-30 carbon atoms per molecule are reacted in the presence of a lower alkanol having from 2 to about 4 carbon atoms, water and a reaction initiating agent. A process for alkali metal bisulfite addition to primary olefins by means of a fast, continuous, one-phase air-initiated reaction system is discussed in U.S. Pat. No. 3,306,931, which uses a 2-propanol/water solvent combination in specific proportions. U.S. Pat. No. 3,271,444 relates to water-soluble salts of n-alkane-1,2-sulfonic-sulfinic acids having 10 to 20 carbon atoms, which are prepared by reacting n-olefins with a bisulfite salt in the presence of an alcohol solvent containing an organic tertiary-butyl perester.
An improved process for making propane sulfonates without isolating intermediates is discussed in U.S. Pat. No. 4,442,042 which involves (1) using an aqueous NaOH system instead of metallic sodium, and (2) recycling a portion of the product surfactant as a phase transfer catalyst to ensure intimate contact of the reactants. As in the process of U.S. Pat. No. 4,267,123, allyl halides are employed, which have toxicity concerns.
The free radical addition of sodium bisulphite to linear olefins (sulphitation) was investigated as described in S. C. Bright, et al., "Alkane Sulphonate Preparation by the Sulphitation of Long Chain Olefins," J. Appl. Chem. Biotechnol., 1975, Vol. 25, pp. 901-912. The kinetic consequences of the probable mechanism of sulphitation were observed to be consistent with the experimental results.
It would be desirable to provide a process which does not require halogen-containing reactants or intermediates and which may also may be made in high yield without appreciable by-products.